EP0766382A2 - Pseudo-logarithmic intermediate-frequency amplifier - Google Patents

Pseudo-logarithmic intermediate-frequency amplifier Download PDF

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Publication number
EP0766382A2
EP0766382A2 EP96119203A EP96119203A EP0766382A2 EP 0766382 A2 EP0766382 A2 EP 0766382A2 EP 96119203 A EP96119203 A EP 96119203A EP 96119203 A EP96119203 A EP 96119203A EP 0766382 A2 EP0766382 A2 EP 0766382A2
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Prior art keywords
gate
differential
transistors
rectifiers
current
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German (de)
English (en)
French (fr)
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EP0766382A3 (ko
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Katsuji Kimura
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NEC Corp
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NEC Corp
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Priority claimed from JP3147769A external-priority patent/JP2692427B2/ja
Priority claimed from JP3155648A external-priority patent/JP3036121B2/ja
Application filed by NEC Corp filed Critical NEC Corp
Publication of EP0766382A2 publication Critical patent/EP0766382A2/en
Publication of EP0766382A3 publication Critical patent/EP0766382A3/xx
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G7/00—Volume compression or expansion in amplifiers
    • H03G7/001—Volume compression or expansion in amplifiers without controlling loop

Definitions

  • This invention relates to a logarithmic intermediate-frequency amplifier, and more particularly, to a logarithmic intermediate-frequency amplifier having pseudo logarithmic characteristic.
  • a logarithmic intermediate-frequency (IF) amplifier comprises IF amplifiers cascade-connected to each other in a multistage connection manner, rectifiers for receiving output signals of these IF amplifiers in a successive manner, and an adder for adding all output signals of these rectifiers to each other, and is generally formed on a bipolar integrated circuit.
  • An MOS transistor is large in 1/f noise, so that it is required to have an intermediate-frequency (IF) band cut off its low band side in order to prevent the sensitivity from being degraded from the viewpoint of a received input.
  • So-called HPF (High Pass Filter) characteristic to cut off this low band side can be equivalently obtained by providing IF amplifiers in a multistage cascade-connection manner through coupling capacitors. In this case, however, a coupling capacitor to be inserted is desired to be small in capacity.
  • the multistage connection of the IF amplifiers through the coupling capacitors makes that the rectifiers receiving output signals of respective IF amplifiers differentiate the signal waveforms thereof, thus making it easy to vary the direct-current value of an output of each rectifier.
  • a pseudo - logarithmic IF amplifier of a polygonal line approximation type formed on a C-MOS integrated circuit such a circuit as is, for example, shown in Fig. 1 is known conventionally.
  • This circuit is disclosed in the Japanese Laid-Open Patent Application No. 62-292010, which comprises n differential amplifiers respectively including MOS transistor pairs (T01, T01), (T02, T02) ..., and (T0n, T0n) and constant-current sources I01, I02, ..., and I0n.
  • These differential amplifiers are cascaded in a n-stage connection manner.
  • the differential amplifiers of the first through nth stages are connected to full-wave rectifiers comprising two pairs of transistors (T11 and Tlk), (T21 and T2k) and (Tnl and Tnk), and n constant-current sources I11, I12, ..., and I1n for driving these two pairs of transistors, respectively.
  • the differential amplifier of the (n+1)th stage has a full-wave rectifier comprising two pairs of MOS transistors ( T(n+1), and T(n+1)k) and two constant-current sources In(n+1) for driving the two pairs of them, and receiving an output signal of the differential amplifier at the nth stage.
  • the transistors having a gate-width (W) and gate-length (L) ratio (W/L) of one (1) or (T11 and T11), (T21 and T21), Vietnamese, and (T(n+1)1 and T(n+1)1) have the drains and gates connected respectively in common, and on the other hand, those having the ratio (W/L) of k, or the transistors (Tlk and T1k), (T2k and T2k), ⁇ , and (T(n+1)k and T(n+1)k) have the drains and gates connected respectively in common.
  • W gate-width
  • L gate-length
  • an adder comprising three MOS transistor pairs (T10, T20), (T30, T40) and (T50, T60) is provided, which sums up the outputs of the full-wave rectifiers of the first to the (n+1)th stages.
  • an output current ⁇ I1 of the two pairs of transistors (T11 and T1k) can be expressed as follows;
  • an output current ⁇ I2 of the two pairs of transistors (T21 and T2k) of the second stage ⁇ , and an output current In+1 of the two pairs of the transistors (T(n+1)1 and T(n+1)k) can be respectively expressed as follows;
  • the maximum output voltages of the differential amplifiers of respective stages can be made of a constant sign.
  • the characteristic of the output current IOUT can be made approximately of a logarithmic characteristic to the input voltage VIN.
  • the conventional pseudo-logarithmic IF amplifier With the conventional pseudo-logarithmic IF amplifier arranged as shown above, it makes one full-wave rectifier of two unbalanced differential transistor pairs and as a result, the constant-current source is required to be used twice in number as many as the rectifier, resulting in arising such a problem that current consumption unavoidably becomes large.
  • one rectifier uses two unbalanced differential transistor pairs and as a result, the circuit scale disadvantageously becomes large.
  • an object of this invention is to provide a logarithmic IF amplifier in which contradictory requirements on the capacity of a coupling capacitor to be inserted can be satisfied thereby to be formed on a C-MOS integrated circuit.
  • Another object of this invention is to provide a pseudo-logarithmic IF amplifier capable of reducing power consumption as well as decreasing circuit scale.
  • a C-MOS logarithmic IF amplifier is provided which is realizable on a C-MOS integrated circuit.
  • a C-MOS logarithmic IF amplifier of this aspect comprises a plurality of IF amplifiers cascade-connected through a first coupling capacitor to each other, a plurality of rectifiers each receiving a signal from the corresponding one of the IF amplifiers through a second coupling capacitor different in capacity from the first coupling capacitor, and an adder for adding the output signals of the rectifiers to each other.
  • the first and second coupling capacitors are preferable to be connected in series to each other thereby cascade - connecting the IF amplifiers therethrough.
  • the rectifiers each is applied with an output signal of the corresponding one of the IF amplifiers at the connection point of the corresponding first and second coupling capacitors.
  • An IF amplifier to be used for this invention is not specifically limited in structure thereby, an arbitrarily structured one can be used therefor, and a rectifier to be used for this invention is not specifically limited in structure thereby, so that either of a half-wave or full-wave rectifier can be used therefor.
  • the IF amplifiers are connected through the first coupling capacitor to each other and the rectifiers are connected to each other through the second coupling capacitor different in capacity from the first coupling capacitor.
  • the IF amplifiers each makes it possible to have its frequency band cut off the low band side thereof, and the rectifiers each makes it possible to have its frequency band expanded to the low band side. Accordingly, (1/f) noise of an IF amplifier can be reduced thereby restricting degradation of noise figure (NF).
  • the input band of a rectifier can be expanded to the low band side thereby obviating excessive signal differentiation and positively maintaining linearity of the logarithmic characteristic. Consequently, the C-MOS logarithmic IF amplifier according to this invention can be realized on a C-MOS integrated circuit.
  • a pseudo-logarithmic IF amplifier is provided which is realizable on a C-MOS integrated circuit.
  • This amplifier has two types, a first and second.
  • a pseudo-logarithmic IF amplifier of the first type comprises a plurality of differential amplifiers cascade-connected in a plurality of stages, a first half-wave rectifier for receiving an input signal of the differential amplifier of a first one of the stages, a plurality of second half-wave rectifiers each receiving an output signal of the corresponding one of the differential amplifiers other than that at the first stage, and an adder for adding the direct-current components of outputs of the first and second rectifiers.
  • the first and second rectifiers each has one or more unbalanced differential transistor pairs different in gate-width and gate-length ratio from each other thereby outputting the direct-current component of a differential output current of the same.
  • a pseudo-logarithmic IF amplifier of the second type comprises a plurality of differential amplifiers cascade-connected in a plurality of stages, a first half-wave rectifier for receiving an input signal of the differential amplifier of a first one of the stages, a plurality of second half-wave rectifiers each receiving an output signal of the corresponding one of the differential amplifiers other than that at the first stage, and an adder for adding outputs of the first and second half-wave rectifiers and outputting the direct-current components thus added, or for receiving outputs of the first and second rectifiers to form their direct-current components thereby to be added to each other.
  • the first and second rectifiers each has one or more unbalanced differential transistor-pairs different in gate-width and gate-length ratio from each other, but different from the first type in that each of them is so structured that is adapted to output its differential output current directly.
  • the transistors each with a relatively small gate-width and gate-length ratio have the drains and gates connected respectively in common, and the transistors each with a relatively large gate-width and gate-length ratio have the drains and gates connected respectively in common.
  • a half-wave rectifier having one or more unbalanced differential transistor-pairs is used as the rectifier, and a direct - current component of its differential output current is added, or its differential output current is added and then, the direct-current component is taken out therefrom.
  • current consumption and circuit scale can be advantageously reduced.
  • Fig. 1 is a circuit diagram showing an example of a conventional pseudo-logarithmic IF amplifier.
  • Fig. 2 is a circuit block diagram of a C-MOS logarithmic IF amplifier (Example 1) .
  • Fig. 3 is a circuit block diagram of a C-MOS logarithmic IF amplifier (Example 2) .
  • Fig. 4 is a circuit diagram showing one example of a rectifier to be used in the amplifier shown in Fig. 2 or 3.
  • Fig. 5 is a circuit diagram showing another example of a rectifier to be used in the amplifier shown in Fig. 2 or 3.
  • Fig. 6 is a circuit diagram of a pseudo-logarithmic IF amplifier according to a first embodiment of this invention.
  • Fig. 7 is a characteristic diagram of the amplifier shown in Fig. 6.
  • Fig. 8 is a circuit diagram of a pseudo-logarithmic IF amplifier according to a second embodiment of this invention.
  • Fig. 9 is a circuit diagram of a pseudo-logarithmic IF amplifier according to a third embodiment of this invention.
  • Fig. 10 is a circuit diagram of a half-wave rectifier to be used in the amplifier shown in Fig. 9.
  • Fig. 2 shows a C-MOS logarithmic IF amplifier according to a first Example in which a plurality of IF amplifiers A1, A2, ⁇ are cascaded in a multistage connection manner in order to amplify an IF signal successively.
  • the multistage cascade - connected amplifiers A1, A2, ⁇ have rectifiers B1, B2, ⁇ connected thereto in order to rectify their output signals, respectively.
  • Output signals of the rectifiers B1, B2, ⁇ are sent to an adder C to be added to each other and outputted.
  • the IF amplifiers A1, A2, ⁇ the rectifiers B1, B2, ⁇ and the adder C are respectively made of MOS transistors.
  • IF amplifiers A1, A2, ⁇ are cascade-connected to each other through the two capacitors which are connected in series between each adjacent two of these IF amplifiers.
  • Each of the IF amplifiers A1, A2, ⁇ is connected to the corresponding one of these rectifiers B1, B2, ⁇ at the connection point of the two capacitors connected in series therebetween.
  • the IF amplifiers A1 and A2 are cascade-connected to each other through the capacitors CA1 and CB1 which are disposed in series therebetween.
  • the IF amplifier A1 is connected to the rectifier B1 at the connection point of the capacitors CA1 and CB1.
  • the IF amplifiers A2 and A3 are cascade-connected to each other through the capacitors CA2 and CB2 which are disposed in series therebetween, and the IF amplifier A2 is connected to the rectifier B2 at the connection point of the capacitors CA2 and CB2.
  • the IF amplifiers A3 and A4, A4 and A5, ⁇ are cascade-connected to each other and connected correspondingly to the rectifiers B3, B4, ⁇ in the same manner as shown above.
  • an input signal to a rectifier Bi is supplied to the gate of a MOS transistor thereof, so that the input impedance becomes high and yet the direct-current biasing to the gate can be made of a high input impedance.
  • a combined capacity Ci of the capacitors CAi and CBi can be approximated as follows; Ci ⁇ (CAi CBi)/(CAi+CBi)
  • the IF amplifiers Ai and A(i+l) are coupled through the combined capacity Ci to each other, and the IF amplifier Ai and the rectifier Bi are coupled to each other through only the capacity of the capacitor CAi.
  • the low band side of a frequency band is determined by the differential characteristic ( HPF characteristic) of each coupling capacitor.
  • HPF characteristic the differential characteristic of each coupling capacitor.
  • the low band side cut-off frequency fcIFi of the IF amplifier Ai can be made high compared with the low band side cut-off frequency fcRECTi of the rectifier Bi.
  • an IF amplifier is allowed the low band side of its frequency band to be cut off and on the other hand, a rectifier is allowed its frequency band to be expanded to the low band side, so that a logarithmic IF amplifier can be obtained which is formed on a C-MOS integrated circuit without arising any important problem.
  • Fig. 3 shows another C-MOS logarithmic IF amplifier (Example 2).
  • an IF amplifier Ai is connected through a capacitor CBi to an IF amplifier A(i+1) and through a capacitor CBi whose capacity is different from that of the capacitor CAi to a rectifier Bi.
  • Other components are arranged as explained in the first embodiment.
  • the C-MOS logarithmic IF amplifier of this embodiment makes it possible to obtain the same effects as shown in Fig. 2.
  • any circuit made of C-MOS transistor can be arbitrarily used as the rectifier Bi.
  • a squaring circuit can be pointed out as an example as shown in Fig. 4, which is disclosed in the Japanese Laid-Open Patent Application No. 63-24377 made by the same one as the inventor of this amplifier, thus being used as a squaring full-wave rectifier.
  • the squaring circuit comprises a first differential transistor-pair consisting of a MOS transistor T1 with a gate-width and gate-length ratio (W1/L1) and a MOS transistor T2 with a gate-width and gate-length ratio (W2/L2) and a second differential transistor-pair consisting of a MOS transistor T3 with the same ratio as that of the transistor T1, (W1/L1), and a MOS transistor T4 with the same ratio as that of the transistor T2, (W2/L2).
  • the ratio (W1/L1) is made one (1)
  • the ratio (W2/L2) is made k.
  • the transistors T1 and T2 have the sources connected in common and the transistors T3 and T4 have the sources connected in common, which are connected through their connection points to constant-current sources 10, respectively.
  • the gate of the transistor T1 is connected to that of the transistor 4, and the gate of the transistor T2 is connected to that of the transistor T3.
  • the collector of the transistor T1 is connected to that of the transistor T3, and the collector of the transistor 2 is connected to that of the collector T4.
  • An input voltage VIN is applied across the common gate of the transistors T1 and T4 and the common gate of the transistors T2 and T3, which are different in the gate-width and gate-length ratio from each other.
  • Transistors T5 and T6 each is the primary side transistor of a current mirror circuit.
  • a subtracting circuit S subtracts a current flowing in the output line of the second differential pair from a current flowing in the output line of the first differential pair.
  • VDD is a voltage source.
  • ⁇ IdI Id1 - Id2
  • ⁇ IdI [-(1+1/k1) (1-1/k1)I0 + 2 ⁇ 1 ⁇ (1+1/K1) ⁇ VIN 2 + 4 ⁇ 1 ⁇ VIN ⁇ (1/K1 1/2 ) ⁇ (1+1/K1)(I0/ ⁇ 1)-VIN 2 ) ⁇ 1/2 ]/(1+1/k1) 2
  • ⁇ IdII Id3 - Id4
  • ⁇ IdII [(1+1/k1) (1-1/k1)I0 + 2 ⁇ 1 ⁇ (1-1/K1)VIN 2 + 4 ⁇ 1 ⁇ VIN (1/K1 1/2 ) ⁇ (1+1/K1)(I0/ ⁇ 1)-VIN 2 ) ⁇ 1/2 ]/(1+1/k1) 2
  • the current difference ⁇ Id includes the square term of the input voltage VIN.
  • the square characteristic can be obtained with a simple circuit arranged as shown in Fig. 4, which comprises two differential pairs each consisting of two transistors different in the gate-width and gate-length ratio (W/L) from each other, and in which the transistors with the same gate-width and gate-length ratio (W/L) have the drains connected in common to each other and yet, their outputs become opposite in phase.
  • Fig. 4 which comprises two differential pairs each consisting of two transistors different in the gate-width and gate-length ratio (W/L) from each other, and in which the transistors with the same gate-width and gate-length ratio (W/L) have the drains connected in common to each other and yet, their outputs become opposite in phase.
  • FIG. 5 Another example of a squaring circuit to be used in these Examples is shown in Fig. 5, which comprises four MOS transistors.
  • MOS transistors M1 and M2 constitute a first differential transistor-pair to be driven by a constant-current source I0
  • MOS transistors M3 and M4 constitute a second differential transistor-pair to be driven by a constant-current source obtained by the following equation; ⁇ 2 ⁇ k2 1/2 /(k2+1) ⁇ I0
  • the drain of the transistor M1 is connected to that of the transistor M3, and the drain of the transistor M2 is connected to that of the transistor M4.
  • the gate of the transistor M1 is connected to that of the transistor M4, and the gate of the transistor M2 is connected to that of the transistor M3.
  • the gate-width (W1) and gate-length (L1) ratio (W1/L1) of the transistor M1 is made one (1)
  • the gate-width (W2) and gate-length (L2) ratio (W2/L2) of the transistor M2 is k2. That is, Eq.(28) can be satisfied between them.
  • the drain currents Id1' and Id2' of the transistors M1 and M2 of the first differential pair can be respectively expressed as follows; where VGS1' and VGS2' show the gate-to-source voltage of the transistors M1 and M2 respectively.
  • Id1' ⁇ n(COX/2) (W1/L1) (VGS1'-VT) 2
  • Id2' ⁇ n(COX/2) k(W1/L1) (VGS2'-VT) 2
  • IdP Id1' - Id2'
  • the squaring circuit comprises two differential pairs each consisting of two transistors whose gate-width and gate-length ratios are optimized thereby making a differential input, so that the squaring circuit is not dependent on variation in threshold voltage due to the forming dispersion of transistors.
  • Fig. 6 shows a pseudo - logarithmic IF amplifier according to a first embodiment of this invention, which comprises n differential amplifier A1', A2', ..., and An' which are cascaded in a n-stage connection manner, a first half-wave rectifier for receiving an input signal to the differential amplifier A1' of the first stage, n second half-wave rectifiers respectively receiving output signals of the differential amplifiers A1', A2', ..., and An' from the first to nth stages, and an adder for adding the output signals of these half-wave rectifiers.
  • the differential amplifiers A1', A2', ..., and An' are of the same in characteristic, and yet, the first and n second half-wave rectifiers are of the same in structure.
  • the first stage half-wave rectifier comprises an unbalanced differential transistor - pair consisting of n-channel MOS transistors M11 and M12 different in gate-width and gate-length ratio from each other, a current mirror circuit consisting of p-channel MOS transistors M13 and M14 for forming a differential current, a capacitor C01 for erasing an alternating current component from the differential current thus formed, and a constant-current source I01, thus outputting the direct-current component of the differential output current.
  • the capacitor C01 is provided between the drains of the transistors M11 and M12, and the constant-current source I01 is provided between their sources connected in common and the ground.
  • the drains of the transistors M13 and M14 connected in common are applied with a source voltage VDD.
  • An input voltage VIN to the differential amplifier A1' is applied between the gates of the transistors M11 and M12.
  • a direct-current component ⁇ I1 ⁇ of the differential output current is applied between the gate of a MOS transistor M10 and that of a M0Stransistor M20 of the adder.
  • the second half-wave rectifier of the second stage has the same structure as that of the first one, and comprises an unbalanced differential transistor-pair consisting of transistors M21 and M22 different in gate-width and gate-length ratio from each other, a current mirror circuit consisting of transistors M23 and M24 for forming a differential current, a capacitor C02 for erasing an alternating current component of the differential current thus formed, and a constant-current source I02, thus outputting the direct-current component of the differential output current.
  • the capacitor C02 is provided between the drains of the transistors M21 and M22, and the constant-current source I02 is provided between their sources connected in common and the ground.
  • the drains of the transistors M23 and M24 connected in common are applied with the source voltage VDD.
  • An output voltage V1 of the differential amplifier A1' is applied between the gates of the transistors M21 and M22.
  • a direct-current component ⁇ I2 ⁇ of the differential output current is applied between the gates of the MOS transistors M10 and M20 of the adder.
  • the second half-wave rectifier of the (n+1)th stage has the same arrangement as above. That is, it comprises an unbalanced differential transistor pair consisting of transistors M(n+1)1 and M(n+1)2 different in gate-width and gate-length ratio from each other, a current mirror circuit consisting of transistors M(n+1)3 and M(n+1)4 for forming a differential current, a capacitor C0(n+1) for erasing an alternating current component from the differential current thus formed, and a constant-current source I0(n+1), thus outputting the direct-current component of the differential output current.
  • the capacitor C0(n+1) is provided between the drains of the transistors M(n+1)1 and M(n+1)2, and the constant-current source I0(n+1) is provided between their sources connected in common and the ground.
  • the drains of the transistors M(n+1)3 and M(n+1)4 connected in common are applied with the source voltage VDD.
  • An output voltage VOUT of the differential amplifier An' is applied between the gates of the transistors M(n+1)1 and M(n+1)2.
  • a direct-current component ⁇ In+1 ⁇ of the differential output current is applied between the gates of the MOS transistors M10 and M20 of the adder.
  • the gate-width and gate-length ratio of each of the transistors M11, M21, ..., and M(n+1)1 is smaller than that of each of the transistors M12, M22, ..., and M(n+1)2.
  • the adder comprises a current mirror circuit consisting of a differential-pair of p channel MOS transistors M10 and M20, thereby adding the output currents of (n+1) half-wave rectifiers, or the direct-current components ⁇ I1 ⁇ , ⁇ I2 ⁇ ,..., and ⁇ In+1 ⁇ outputted from respective half - wave rectifiers.
  • the unbalanced differential transistor-pairs of respective half-wave rectifiers are not necessary to have a gate-width and gate-length ratio equal to each other, however, it is made equal to each other in this explanation for the simplification purpose.
  • I1 I1DC + I1SQ + I1DIFF
  • ⁇ I1DC ⁇ -(K3-1)/(k3+1) ⁇ I01
  • ⁇ I1SQ ⁇ 2k3(k3-1) ⁇ 3/(k3+1) 2
  • the I1DIFF may be considered to be a direct-current characteristic of generally so-called balanced differential - pair that is approximately proportional to the input voltage VIN, thus becoming the alternating current component to be erased by the capacitor C01.
  • the direct-current component ⁇ I1 ⁇ of ⁇ I1 becomes the sum of ⁇ I1DC and a direct-current component ⁇ I1SQ ⁇ of the ⁇ I1SQ as shown by the following equation (72), and if the input voltage VIN is supposed to be of a sine wave and expressed as the following equation (73), the direct-current component ⁇ I1 ⁇ can be obtained by the following equation (74);
  • cos (2 ⁇ ft) ⁇ I1 ⁇ k3 - 1 k3 + 1 I01 + k3 k3-1 ⁇ 3 ⁇ I1 k3 + 1 2
  • 2 ⁇ In+1 ⁇ k3 - 1 k3 + 1 I0 n+1 + k3 k3-1 ⁇ 3 k3 + 1 2
  • IRSSI ⁇ I1 ⁇ + ⁇ I2 ⁇ + ⁇ + ⁇ In+1 ⁇
  • the output voltage VRSSI can be obtained as follows; where RRSSI is a load registance.
  • the pseudo - logarithmic IF amplifier may have a capacitor disposed on the adder side thereof.
  • the half-wave rectifiers and the adder may be arranged, for example, as follows;
  • Fig. 8 shows an second embodiment of this invention.
  • the half-wave rectifier each comprises one unbalanced differential transistor-pair, thereby directly outputting a differential output current.
  • the adder has a current mirror circuit consisting of p-channel MOS transistors M30 and M40 for forming a differential current and a capacitor CO for erasing an alternating current component from the differential current thereby to form the direct-current component and added.
  • the capacitor C0 is arranged between the gates connected in common of the p - channel MOS transistors M10 and M20 and the drain of the transistor M20. The other arrangement is same as the first embodiment.
  • the half-wave rectifier each comprises one unbalanced differential transistor-pair, so that the amplifier of this embodiment is largely effective to make the circuit scale small.
  • Fig. 9 shows an third embodiment of this invention.
  • the capacitor C0 is arranged between the output terminal and the ground.
  • the other arrangement is same as the second embodiment.
  • the adder may have the capacitor C0 disposed on the output side thereof.
  • the direct-current component is taken out after adding all the differential currents.
  • This circuit is also largely effective to make the circuit scale small.
  • each can be formed of at leaset one unbalanced differential transistor-pair.
  • a rectifier with two unbalanced differential transistor-pair is exemplified in Fig.10, which is obtained by connecting the unbalanced differential transistor-pair (M11, M12) of the first embodiment shown in Fig. 6 and an unbalanced differential transistor-pair (M15, M16) in parallel.
  • the unbalanced differential transistor-pairs (M11, M12) and (M15, M16) are respectively driven by different constant-current sources I01 and I01' from each other.
  • the transistors M11 and M15 each with a small gate-width and gate-length ratio have the drains and gates connected in common, and the transistors M12 and M16 each with a large gate-width and gate-length ratio have the drains and gate connected in common.
  • a pseudo-logarithmic IF amplifier of this invention makes it possible to reduce currrent consumption as well as to decrease the circuit scale.
  • the half-wave rectifiers each is formed of two or more unbalanced differential transistor-pairs, the logarithmic characteristic can be effectively improved in linearity.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
EP96119203A 1991-05-23 1992-05-22 Pseudo-logarithmic intermediate-frequency amplifier Withdrawn EP0766382A2 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP147769/91 1991-05-23
JP3147769A JP2692427B2 (ja) 1991-05-23 1991-05-23 Ｃ−ｍｏｓ対数ｉｆ増幅器
JP155648/91 1991-05-30
JP3155648A JP3036121B2 (ja) 1991-05-30 1991-05-30 擬似対数ｉｆ増幅器
EP92108690A EP0514929B1 (en) 1991-05-23 1992-05-22 Logarithmic intermediate-frequency amplifier

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EP92108690A Division EP0514929B1 (en) 1991-05-23 1992-05-22 Logarithmic intermediate-frequency amplifier
EP92108690.6 Division 1992-05-22

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EP0766382A2 true EP0766382A2 (en) 1997-04-02
EP0766382A3 EP0766382A3 (ko) 1997-04-16

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EP92108690A Expired - Lifetime EP0514929B1 (en) 1991-05-23 1992-05-22 Logarithmic intermediate-frequency amplifier

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US (1) US5467046A (ko)
EP (2) EP0766382A2 (ko)
KR (1) KR960015009B1 (ko)
AU (2) AU658182B2 (ko)
CA (1) CA2069243C (ko)
DE (1) DE69230014T2 (ko)
ES (1) ES2136066T3 (ko)
HK (1) HK1009059A1 (ko)
SG (1) SG48040A1 (ko)

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AU1011295A (en) 1995-03-09
AU1714492A (en) 1992-11-26
SG48040A1 (en) 1998-04-17
EP0514929B1 (en) 1999-09-22
HK1009059A1 (en) 1999-05-21
DE69230014D1 (de) 1999-10-28
CA2069243C (en) 1997-08-19
KR960015009B1 (ko) 1996-10-23
US5467046A (en) 1995-11-14
EP0766382A3 (ko) 1997-04-16
AU658182B2 (en) 1995-04-06
CA2069243A1 (en) 1992-11-24
EP0514929A3 (ko) 1994-03-30
DE69230014T2 (de) 2000-03-23
KR920022646A (ko) 1992-12-19
EP0514929A2 (en) 1992-11-25
ES2136066T3 (es) 1999-11-16
AU677470B2 (en) 1997-04-24

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